Electric starter motors



Dec. 19, 1967 J. G. w. WEST 3,

ELECTRIC STARTER MOTORS Filed June 28, 1965 4 Sheets-Sheet l Dec. 19, 1967 J. G. w. WEST ELECTRIC STARTER MOTORS 4 Sheets-Sheet 2 Filed June 28, 1965 F/ ///H I 2 E12 7/4 /W L5 d@\ 5 Q Dec. 19, 1967 ,1. G. w. WEST ELECTRIC STARTER MOTORS 4 Sheets-Sheet 3 Filed June 28, 1965 Dec. 19, 1967 J. G. w. WEST ELECTRIC STARTER MOTORS 4 Sheets-Sheet :1

Filed June 28, 1965 United States Patent 3,359,440 ELECTRIC STARTER MOTORS John Godfrey Wilson West, Sutton Coldfield, England,

assignor to Joseph Lucas (Industries) Limited, Birmingham, England, a British company Filed June 28, 1965, Ser. No. 467,334 Claims priority, application Great Britain, July 8, 1964, 28,098/64 4 Claims. (Cl. 310-75) ABSTRACT OF THE DISCLOSURE An electric starter motor for engaging a pinion with a toothed wheel on an engine to be started includes a plurality of pole pieces at least one of which has a fixed part and a movable part mounted on a rod, the rod and movable part being resiliently biased away from the fixed part in a direction parallel to the motor shaft. The rod is connected to the pinion and when the motor is energised the movable part is attracted to the fixed part to cause the pinion to engage the toothed wheel to start the engine.

This invention relates to electric starter motors of the kind in which energisation of the motor causes a pinion to be moved from an inoperative position to an operative position in which in use the pinion engages a toothed wheel on the engine to be started.

In one aspect, the invention resides in a starter motor of the kind specified, the motor including a part movable in a direction parallel to the motor shaft and connected to the pinion, and resilient means urging said part to a position in which the pinion is in its inoperative position, the arrangement being such that when the field system of the motor is energised said part will be attracted by one or more pole pieces of the motor to cause the pinion to be moved to its operative position.

In anther aspect, the invention resides in a starter motor of the kind specified, the motor including at least one pole piece having a fixed part and a movable part resiliently urged away from the fixed part in a direction parallel to the motor shaft, and means connecting the movable part to the pinion, the arrangement being such that when the field system of the motor is energised, the movable part will be attracted by the fixed part and the pinion will be moved from its inoperative position to its operative position.

In the accompanying drawings:

FIGURE 1 is a longitudinal section through the stator assembly of a motor according to one example of the invention,

FIGURE 2 is a longitudinal section through the motor taken at right angles to FIGURE 1,

FIGURE 3 is a cross-section of the stator assembly, and FIGURE 4 is a longitudinal section illustrating the second example.

Referring to FIGURES l to 3, there is provided a cylindrical iron yoke 18 having an end plate 23 at one end thereof. On the interior of the yoke are four equi-angularly spaced pole pieces 19, 20, 21, 22. Each pole piece extends axially relative to the yoke and is formed with one flat end and one rounded end, the arrangement being such that adjacent rounded ends are to opposite axial ends of the yoke. The yoke 18 carries bearings 16 supporting the rotor shaft on which the armature assembly 14 is mounted.

The pole pieces serve to hold in position a field coil 17 formed from flat strip. The strip is first wound to helical form with the flat faces of the strip in contact, and is then bent about a diametrical plane so that if the 3,359,440 Patented Dec. 19, 1967 coil were considered in developed view it would be sinusoidal. When in position in the yoke, the coil has portions which extend substantially axially relative to the yoke and are trapped in spaces between the pole pieces, and curved portions joining the axial portions and extending around the rounded ends of the pole pieces. One end of the coil 17 is earthed by way of a terminal on the yoke 18, and its other end is connected to a pair of diametrically opposite brushes engaging slip rings on the armature assembly 14. The assembly 14 further incorporates a second pair of slip rings positioned at to the first pair and engaged by brushes which in use are connected to a DC. source.

The pole pieces 20, 22 are secured to the yoke by bolts 24, and in assembly are secured to the yoke after the coil has been placed in position. The pole pieces 19, 21 are each formed in two parts labelled a and b (FIGURE 2), the parts 19a, 210 being permanently secured to the yoke 18 and incorporating the rounded ends, and the parts 1%, 21b being fixed to rods 28 and being axially movable in a direction parallel to the rotor shaft 15. It will be appreciated that such movement is not hindered with the particular form of winding described. Any convenient resilient means 26 is utilised for urging the movable parts 1%, 21b of the pole pieces away from the fixed parts 19a, 21a, and further means is provided for connecting the movable parts with a conventional pinion and clutch assembly 27 on the shaft 15. The arrangement is such that when the field coil 17 is energised, the movable pole parts 1%, 21b are attracted by the fixed pole parts 19a, 21a and serve to engage the pinion with a toothed wheel on an engine to be started. Energisation of the armature windings then starts the engine.

The construction of the motor may take a variety of forms. As show, the movable pole parts 1%, 21b are fixed on rods 28 which rods slide within fixed pole parts 19a, 21a and extend parallel to the motor shaft 15 through the end plate 23 of the motor. At their ends the rods 28 are formed with flanges 29 which act on the assembly 27 to move it into engagement with the toothed wheel (not shown). Springs surrounding the rods and acting between the flanges 29 and end plate 23 serve as the resilient means. The rods could be secured to the assembly 27 through links or in any other convenient manner, and the assembly 27 could be moved towards or away from the motor, de pending on the type of starter. Moreover, the form of field coil 17 shown in FIGURES 1 to 3 is particularly suitable for use with the present invention because the parts 19b, 21b are free to slide axially. However, the invention can be applied to other forms of motors for example a motor with two wound poles and two consequential poles. In such a motor, the unwound pole pieces can be formed in two parts as in the arrangement shown in FIGURES 1 to 3.

FIGURE 4 illustrates, partly in diagrammatic form, an alternative arrangement in which the motor includes a two part yoke 31, 32, the part 31 having one pair of pole pieces, 33, 34 formed integrally therewith, and the other pair of pole pieces (not shown) being formed integrally with the part 32. The field coil 35 is similar to the coil 17 shown in FIGURES 1 to 3, and the yoke supports the rotor shaft 36, on which are mounted the armature assembly 37 and the pinion and clutch assembly 38. In this construction, no part of any of the poles is free to move, but an annular ring 39 is provided which is supported by links 40 having their midpoints pivotally connected to parts secured to the yoke, and their ends pivotally connected respectively to the ring 39 and to the assembly 38. The ring 39 is urged away from the pole pieces by any convenient resilient means which in the example shown consists of a :pair of springs 41, 42 acting between the ring 39 and pzirts 33a, 34a of the pole pieces. It will be noted that the parts 33a, 34a extend axially beyond the coil 35, and the arrangement is such that when the coil 35 is energised the ring 39 is attracted by the parts 33a, 34a and acts through the links 40 to engage the pinion with a toothed wheel on the engine. Preferably, the ring 39 carries a contact piece which, when the pinion has engaged the toothed Wheel, contacts a fixed contact piece to complete a circuit to the armature assembly.

The arrangement shown in FIGURE 4 can be utilised in motors having all their poles individually wound, provided that the pole pieces to which a ring corresponding to the ring 39 is to be attracted are formed with parts extending axially beyond the appropriate field coil.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electric starter motor including a housing, a pinion mounted on the motor shaft, a plurality of pole pieces, at least one pole piece having a first part fixed to said housing and a second part mounted on a rod, said rod and second part being resiliently biased away from said first part in a direction parallel to said motor shaft, means connecting said rod to said pinion, and means for setting up a magnetic field in said first part to attract said second part and rod to cause said pinion to be moved from an inoperative position to an operative position thereby engaging a toothed wheel on the engine to be started.

2. An electric starter motor as claimed in claim 1 wherein said plurality of pole pieces is an even number 10 wherein said first part has a cavity for receiving one end of said rod, the other end of said rod carrying said means for connecting said rod to said pinion.

References Cited 15 UNITED STATES PATENTS 3,223,863 12/1965 Preece 310-75 3,177,728 4/1965 Farison 31083 2,813,206 11/1957 Jensen 31077 2,710,359 6/ 1955 NiXson 31076 2,670,449 2/ 1954 Brice 310-209 2,059,624 11/1936 Collins 31078 2,073,444 3 1937 Collins 310-78 1,837,974 12/1931 Lillard 310-78 25 FOREIGN PATENTS 1,120,570 12/1961 Germany.

. MILTON O. HIRSHFIELD, Primary Examiner.

and alternating poles have said first and second parts. 30 J. D. MILLER, Examiner. 

1. AN ELECTRIC STARTER MOTOR INCLUDING A HOUSING, A PINION MOUNTED ON THE MOTOR SHAFT, A PLURALITY OF POLE PIECES, AT LEAST ONE POLE PIECE HAVING A FIRST PART FIXED TO SAID HOUSING AND A SECOND PART MOUNTED ON A ROD, SAID ROD AND SECOND PART BEING RESILIENTLY BIASED AWAY FROM SAID FIRST PART IN A DIRECTION PARALLEL TO SAID MOTOR SHAFT, MEANS CONNECTING SAID ROD TO SAID PINION, AND MEANS FOR SETTING UP A MAGNETIC FIELD IN SAID FIRST PART TO ATTRACT SAID SECOND PART AND ROD TO CAUSE SAID PINION TO BE MOVED FROM AN INOPERATIVE POSITION TO AN OPERATIVE POSITION THEREBY ENGAGING A TOOTHED WHEEL ON THE ENGINE TO BE STARTED. 